Food handlers were sent for stool screening, and food and environmental samples were taken for testing.

FoodTalks declined to comment when contacted. According to its website, it was established in 2004 and it provides catering services for corporate and private functions, and packet meals for school camps and company luncheons.

Ms Diyana Sudarsono’s six-year-old daughter, who attended Small Wonder pre-school in Sengkang, was among those affected.

Ms Sudarsono, 32, said her daughter felt unwell after eating fried macaroni for lunch. “She was quite lucky, she had a bit of abdominal cramps in the evening and the school told us to bring her to a doctor,” she said.

Her daughter was well enough to return to school on Tuesday, but some of her friends had more severe symptoms.

Another parent, who wants to be identified only as Alice, said her son’s friends had fallen ill after eating the packed food provided.

“His friends had watery stools after eating some of the packed food, but they were able to attend school today,” the 37-year-old said on Wednesday.

A teacher from a pre-school which also participated in the camp said children from her centre have mostly recovered, and many of them returned to school on Tuesday. She declined to be named.

This is the third in a series of high-profile food-poisoning incidents that have occurred in the last month.

Last week, 190 people fell ill after eating food prepared by TungLok Catering at the Max Atria at Singapore Expo.

More than 1,000 bento boxes were prepared for the Singapore Civil Defence Force’s public exhibition Lifesavers’ Connect, which was held from last Friday to Sunday. None of the 190 affected were hospitalised.